This disclosure is directed to a sample collection apparatus. Many petroleum or chemical products are priced according to the total volume delivered and the percentage constituents within that volume. Typically, the constituents will have differing values. One constituent will be more valuable than the other. A sampling apparatus is connected to the supply line, and it draws off samples at a proportional to flow. As sample is collected, it accumulates in a container of the sort disclosed herein. The sample may sit for a substantial period of time in all sorts of weather. In the summer, it will be exposed to elevated temperatures, while low temperatures may be experienced during the winter. There is always the possibility and, indeed, depending on the mix of chemicals, the likelihood that the sample will stratify during accumulation. The sample itself is typically broken down into smaller lots for analysis. The sample will typically be in the range of about one to ten liters, and the larger volumes are most unwieldy at the time of testing.
The present invention is directed to an improved sample collection apparatus which particularly enables the sample to be stirred. The constituent sample components are thus mixed together, thereby overcoming sample stratification. The sample is stirred by hand agitating a stirring rod which extends through the sample chamber. As the stirring plate is raised and lowered, it flushes the sample around the ends and creates internal turbulence to mix the sample.
The present invention has the particular advantage that the stirring rod extends all the way through the sample chamber. Because of this, it maintains a fixed displacement in the chamber. This avoids the build up of pressure should the rod not extend fully through the chamber. As more rod is inserted into the chamber, pressures would otherwise rise, and this is highly undesirable.
In an alternate embodiment of the present invention, the stirring rod extends all the way through the apparatus and is encapsulated in chambers adapted to operate at reduced pressures and ideally at equalized pressures. This avoids formation of a pressure or force differential acting across the stirring rod. Indeed, it is possible to impose such a pressure differential on the stirring rod that the rod cannot be easily reciprocated against that pressure.